Experimental and numerical study on the influence of imperfections on the buckling load of unstiffened CFRP shells

Schillo, Conny; Röstermundt, Dirk; Krause, Dieter

doi:10.1016/j.compstruct.2015.04.032

Cited by 48 publications

(22 citation statements)

References 14 publications

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“…A similar setup using the same testing facility has been successfully applied to characterize the influence of imperfections on the buckling of CFRP shells. 16 In combined tension and bending tests, the loads are applied in two sequential steps. First, a pretension is applied at a displacement rate of 1.5 mm/min until a predefined axial load is attained.…”

Section: Combined Loading Tests Using a Six Dof Test Rigmentioning

confidence: 99%

Prototyping and testing of composite riser joints for deepwater application

Chen

Seemann

Krause

et al. 2015

Journal of Reinforced Plastics and Composites

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The high strength to weight ratio, good corrosion resistance, and excellent fatigue property make carbon fiber-reinforced plastics a competitive material solution to replace steel in deepwater riser application. In this work, scaled-down composite riser joints were fabricated using a filament-winding machine. The prototypes comprise several carbon fiberreinforced plastic layers wound over an aluminum liner. They consist of a middle tubular section and two metalcomposite interface end fittings for the transfer of load between joints. A series of mechanical tests, including tension and combined tension-bending loading tests were performed to characterize their structural capacity and evaluate the improvement in performance over a purely metallic mandrel. In addition, finite element analyses incorporating elasticplastic properties of the metallic liner, interfacial failure, and complex carbon fiber-reinforced plastics failure modes were carried out. The numerical predictions are in good agreement with the experimental measurements. The experimentally verified FE framework was then extended to design and analyze a full-scale composite riser model for performance prediction to accelerate the application of composite risers by shortening product development cycle and reducing prototyping costs.

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Section: Combined Loading Tests Using a Six Dof Test Rigmentioning

confidence: 99%

Prototyping and testing of composite riser joints for deepwater application

Chen

Seemann

Krause

et al. 2015

Journal of Reinforced Plastics and Composites

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“…The geometric imperfection signatures are represented by only two imperfection modes and the corresponding amplitudes are defined as the root mean square of the imperfection signatures. However, the buckling load is not only reduced by geometric imperfection [41] but also by deviation of the ideal positioning of the loading [11], [42] as well as thickness deviations [43]. In the particular case of composite shells [44] additional effects become crucial: deviation of the resin distribution or the ply-angles [45], [46].…”

Section: Introductionmentioning

confidence: 99%

Probabilistic and deterministic lower-bound design benchmarks for cylindrical shells under axial compression

Wagner

Hühne

Elishakoff

2020

Thin-Walled Structures

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This article contains examples to demonstrate the use of different design concepts for cylindrical shells under axial compression. The examples are based on shells which were manufactured according to electroplating, machining, welding (isotropic cylinders) and prepreg hand layup on a mandrel (composite cylinders). Three of the four shell series are characterized by pure elastic buckling and one shell series buckled in the elastic-plastic region. All relevant data for the numerical analysis are described in the article and summarized in the Elsevier repository of this article (geometry, material, measured imperfection data and Python-ABAQUS scripts). The design concepts are based on the geometric imperfection signatures, probabilistic and deterministic lower-bound methods. The design concepts are representative for the development of design approaches for imperfection sensitive shells from the early 1980 to the late 2010 and are validated with experimental data. Recently developed design lower-bound curves for axially loaded cylinders are presented and compared with currently used design criteria like the Eurocode EN 1993-1-6 and the NASA SP-8007. The results of this article show that the design of imperfection sensitive cylinders has been significantly improved in the last 30 years.

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“…Imperfections in composite shells can be of geometrical, structural, material nature, or related to loading of the shell. When an imperfection signature of a shell can be determined in sufficient detail, a nonlinear numerical buckling analysis allowing for imperfections provides a close estimate of the buckling load [ 12 , 13 , 14 , 15 ]. Notably, shells sensitive to geometrical imperfections also exhibit sensitivity to load imperfections [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…Notably, shells sensitive to geometrical imperfections also exhibit sensitivity to load imperfections [ 16 ]. It precludes neglecting either group of imperfections, although the relative contribution of different types of imperfections to facilitating the onset of instability may vary [ 12 , 15 , 17 ]. The incorporation of measured initial geometric and thickness imperfections, thickness-adjusted material property variations, measured loading imperfections, elastic radial support conditions, and allowing for selected specimen parameter uncertainties (e.g., uncertainty in the imperfection measurement accuracy, fiber and matrix properties, fiber volume fraction, etc.)…”

Section: Introductionmentioning

confidence: 99%

“…When an actual shell is produced, its imperfection signature can be determined, or vibration tests conducted, in order to characterize the specific shell. The advantage of imperfection characterization with a subsequent numerical modelling of instability onset [ 12 , 13 , 14 , 15 ] is that no mechanical tests of the shell are needed. However, a sufficiently detailed characterization of shell imperfections may be overly complicated in industrial applications.…”

Section: Introductionmentioning

confidence: 99%

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Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression

et al. 2020

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Thin-walled carbon fiber reinforced plastic (CFRP) shells are increasingly used in aerospace industry. Such shells are prone to the loss of stability under compressive loads. Furthermore, the instability onset of monocoque shells exhibits a pronounced imperfection sensitivity. The vibration correlation technique (VCT) is being developed as a nondestructive test method for evaluation of the buckling load of the shells. In this study, accuracy and robustness of an existing and a modified VCT method are evaluated. With this aim, more than 20 thin-walled unstiffened CFRP shells have been produced and tested. The results obtained suggest that the vibration response under loads exceeding 0.25 of the linear buckling load needs to be characterized for a successful application of the VCT. Then the largest unconservative discrepancy of prediction by the modified VCT method amounted to ca. 22% of the critical load. Applying loads exceeding 0.9 of the buckling load reduced the average relative discrepancy to 6.4%.

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Experimental and numerical study on the influence of imperfections on the buckling load of unstiffened CFRP shells

Cited by 48 publications

References 14 publications

Prototyping and testing of composite riser joints for deepwater application

Prototyping and testing of composite riser joints for deepwater application

Probabilistic and deterministic lower-bound design benchmarks for cylindrical shells under axial compression

Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression

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